java - MySQL 异常 - com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException

Question

我得到错误:

'Unknown column 'customerno' in 'field list' '.

但是，该列存在于我的客户表中。那为什么我会得到这个异常？

代码:

import java.sql.*;  

public class Classy {  

    static String myQuery =   
            "SELECT customerno, name" +  
            "FROM customers;";  

    public static void main(String[]args)  
    {  
        String username = "cowboy";  
        String password = "1234567";  
        try  
        {  
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Business", username, password);  
            Statement stmt = con.createStatement();  
            ResultSet rs = stmt.executeQuery(myQuery);  

            while(rs.next())  
            {  
                System.out.print(rs.getString("customerno"));  
            }

        } catch(SQLException ex){System.out.println(ex);}  

    }  

}  

Answer 1

看看您的查询到底是什么。这:

static String myQuery =   
        "SELECT customerno, name" +  
        "FROM customers;";  

相当于:

static String myQuery = "SELECT customerno, nameFROM customers;";  

现在你能看出哪里出了问题吗？我很惊讶它提示 customerno 而不是缺少 FROM 部分...

请注意，我怀疑您也不想要 ;。如果可以的话，我会把它全部写成一行只是为了可读性，同时限制可访问性并使其成为最终版本:

private static final String QUERY = "SELECT customerno, name FROM customers";